/Engine/Source/Runtime/Net/Core/Classes/Net/Serialization/FastArraySerializer.h
If a function with the signature void PostReplicatedReceive(const FFastArraySerializer::FPostReplicatedReceiveParameters& Parameters) is defined in the derived struct It will be called after each call to NetDeltaSerialize on the receiving end, including if we have mapped some unmapped objects
struct FPostReplicatedReceiveParameters
uint32:  1U
bHasMoreUnmappedReferences
int32
OldArraySize
This is the size that the array had before the receive.